1. Field of the Invention
The present invention relates to a sliding door disposed within a doorway of high speed transport vehicles and the like whose outer surface must be very smooth or stream-lined so as to decrease the air resistance upon the outer surface of the structure.
2. Background of the Invention
According to the conventional structure with sliding doors, as shown in FIG. 10, a sliding door D reciprocally moves along the inside of a door pocket A. When moving toward the left, the sliding door D comes into contact with a stopper S comprising a buffer member so as to close the doorway O.
Therefore, the sliding door D which is closed inevitably develops a step of a size l relative to the door pocket A so as to produce a large amount of air resistance when the moving member runs at high speeds.
In high speed vehicles such as for example, the Shinkansen-rail way, sub-ways, mono-rail cars and the like in particular, it is an important requirement to decrease the air resistance, to decrease the running resistance and, hence to effectively use the vehicle power. This tendency becomes more important as the running speed increases.
The air resistance upon the surface of the structure such as, for example, the car body can be reduced very effectively by smoothing the outer surface of the structure. With the conventional sliding door structure, however, it is not possible to eliminate the step defined between the door pocket and the sliding door of the structure, and it is not possible to minimize the air resistance by smoothing the outer surface of the structure.
There has heretofore been proposed a plug-type door for smoothing the outer surface of a vehicle body. However, the plug-type door is generally moved manually and must be, as a whole, moved in two steps, that is, in a direction in which the door is closed and in a direction at right angles therewith and, the movement is generally made upon a continuous curve so that a complex structure is required for limiting the motion of the door and controlling it remotely.
Furthermore, when the presently employed sliding door structure having a step defined between the door pocket and the sliding door is intended to be modified into the plug-type door system, it requires great modification which is virtually impossible to carry out.